Added private API function _PyInstance_Lookup(). This is part of

backporting fixes so that garbage collection doesn't have to trigger
execution of arbitrary Python code just to figure out whether
an object has a __del__ method.

diff --git a/Include/classobject.h b/Include/classobject.h
index c79f4a22ec31b6f6115e488cd5dcf6a78fdfe332..16af37beed910a0e054cdfe7a10cbecb2c449925 100644 (file)
--- a/Include/classobject.h
+++ b/Include/classobject.h
@@ -51,6 +51,18 @@ extern DL_IMPORT(PyObject *) PyMethod_Function(PyObject *);
 extern DL_IMPORT(PyObject *) PyMethod_Self(PyObject *);
 extern DL_IMPORT(PyObject *) PyMethod_Class(PyObject *);
 
+/* Look up attribute with name (a string) on instance object pinst, using
+ * only the instance and base class dicts.  If a descriptor is found in
+ * a class dict, the descriptor is returned without calling it.
+ * Returns NULL if nothing found, else a borrowed reference to the
+ * value associated with name in the dict in which name was found.
+ * The point of this routine is that it never calls arbitrary Python
+ * code, so is always "safe":  all it does is dict lookups.  The function
+ * can't fail, never sets an exception, and NULL is not an error (it just
+ * means "not found").
+ */
+PyAPI_FUNC(PyObject *) _PyInstance_Lookup(PyObject *pinst, PyObject *name);
+
 /* Macros for direct access to these values. Type checks are *not*
    done, so use with care. */
 #define PyMethod_GET_FUNCTION(meth) \

diff --git a/Objects/classobject.c b/Objects/classobject.c
index c1c4a3ebf507ffa0cc6edd6785007ea126ae68fa..90f169e64363ea75df21db15bfa2e7282588e932 100644 (file)
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -729,6 +729,27 @@ instance_getattr(register PyInstanceObject *inst, PyObject *name)
        return res;
 }
 
+/* See classobject.h comments:  this only does dict lookups, and is always
+ * safe to call.
+ */
+PyObject *
+_PyInstance_Lookup(PyObject *pinst, PyObject *name)
+{
+       PyObject *v;
+       PyClassObject *class;
+       PyInstanceObject *inst; /* pinst cast to the right type */
+
+       assert(PyInstance_Check(pinst));
+       inst = (PyInstanceObject *)pinst;
+
+       assert(PyString_Check(name));
+
+       v = PyDict_GetItem(inst->in_dict, name);
+       if (v == NULL)
+               v = class_lookup(inst->in_class, name, &class);
+       return v;
+}
+
 static int
 instance_setattr1(PyInstanceObject *inst, PyObject *name, PyObject *v)
 {
@@ -1056,7 +1077,7 @@ sliceobj_from_intint(int i, int j)
        start = PyInt_FromLong((long)i);
        if (!start)
                return NULL;
-       
+
        end = PyInt_FromLong((long)j);
        if (!end) {
                Py_DECREF(start);
@@ -1088,9 +1109,9 @@ instance_slice(PyInstanceObject *inst, int i, int j)
                if (func == NULL)
                        return NULL;
                arg = Py_BuildValue("(N)", sliceobj_from_intint(i, j));
-       } else 
+       } else
                arg = Py_BuildValue("(ii)", i, j);
-               
+
        if (arg == NULL) {
                Py_DECREF(func);
                return NULL;
@@ -1219,7 +1240,7 @@ instance_contains(PyInstanceObject *inst, PyObject *member)
                res = PyEval_CallObject(func, arg);
                Py_DECREF(func);
                Py_DECREF(arg);
-               if(res == NULL) 
+               if(res == NULL)
                        return -1;
                ret = PyObject_IsTrue(res);
                Py_DECREF(res);
@@ -1292,7 +1313,7 @@ static PyObject *coerce_obj;
 
 /* Try one half of a binary operator involving a class instance. */
 static PyObject *
-half_binop(PyObject *v, PyObject *w, char *opname, binaryfunc thisfunc, 
+half_binop(PyObject *v, PyObject *w, char *opname, binaryfunc thisfunc,
                int swapped)
 {
        PyObject *args;
@@ -1300,7 +1321,7 @@ half_binop(PyObject *v, PyObject *w, char *opname, binaryfunc thisfunc,
        PyObject *coerced = NULL;
        PyObject *v1;
        PyObject *result;
-       
+
        if (!PyInstance_Check(v)) {
                Py_INCREF(Py_NotImplemented);
                return Py_NotImplemented;
@@ -1654,7 +1675,7 @@ bin_power(PyObject *v, PyObject *w)
 /* This version is for ternary calls only (z != None) */
 static PyObject *
 instance_pow(PyObject *v, PyObject *w, PyObject *z)
-{      
+{
        if (z == Py_None) {
                return do_binop(v, w, "__pow__", "__rpow__", bin_power);
        }
@@ -1723,7 +1744,7 @@ instance_ipow(PyObject *v, PyObject *w, PyObject *z)
 #define NAME_OPS 6
 static PyObject **name_op = NULL;
 
-static int 
+static int
 init_name_op(void)
 {
        int i;